An instrument for assembling two board-shaped bodies has hitherto been known, as is disclosed in Japanese Utility Model Laid-Open No. 19117/1986. The disclosed instrument comprises a first member which is adapted to be threaded onto one board-shaped body and comprises a vertical mounting piece and a tongue piece integrally extending from the mounting piece, and a second member which is adapted to be threaded onto the other board-shaped body and has a screw member provided for the fastening as well as a horizontal top plate formed with a through screw hole into which the screw member is threaded. With this known instrument, the tongue plate is fitted into a fitting cavity formed below the through screw hole of the second member and, thereafter, the screw member is fastened. By this operation, the tapered shaft portion of the screw member is brought into contact with the edge at the tip of an elongated hole formed through the tongue piece, and the first member is fastened onto the second member, thereby assembling the two board-shaped bodies.
However, the above-described assembling instrument in which both the first and second members are threaded onto the board-shaped bodies encounters a problem in that, particularly when the board-shaped bodies are pieces of compressed plywood, such as particle board, if the screw is fastened excessively tight or if a large load is applied to the assembling instrument, the screw may become loosened or disengaged.
The present invention has been developed in order to solve the above-stated problem, and an object of the present invention is to provide an assembling instrument which is capable of firmly assembling board-shaped bodies even when the instrument is used to assemble pieces of compressed plywood such as particle board.